Callery pear in flower on a berm just off US 20. Photo provided by Jeff Burbrink.

By Jeff Burbrink
Ag & Natural Resources Extension Educator, Purdue Extension LaGrange County

LAGRANGE — As you go about your business this third week of April in northern Indiana, you will notice some flowering trees with beautiful white blossoms appearing everywhere. Some are in lawns, some at your place of business, and some can be seen along roads, fence rows and along the edges of forested areas.

Jeff Burbrink

These are Callery pears, an ornamental pear tree. For decades, the Callery pear has been a staple in the landscape. You may know them as the cultivar Bradford pear.

Bradford pears were a miracle of sorts when they were first released. They grow under a wide variety of conditions and tolerate harsh environments like downtown New York City. They were self-infertile, meaning they did not reproduce because their pollen did not create viable seeds. Add to that the trees are relatively disease and insect free, and you have what might be considered the perfect tree for the landscape, right?

There are some issues with Bradford pears, however. The biggest issue with the Bradford cultivar of the Callery pear is the way the branches grow upright, with narrow branch angles that are weak and brittle. Because of this architecture, Bradfords have developed a reputation of being a tree with frequent breaks or splits at the trunk or major limbs, especially during storms.

Plant breeders, of course, set to work to rectify this situation, creating new ornamental pear cultivars such as aristocrat, redspire and whitehouse, all of which have improved limb structure. Problem solved, right?

Unfortunately, no. The new cultivars are just enough different from the Bradfords that they can pollenate each other. The result: is hundreds of new wild “volunteer” pear trees popping up where pear trees have not been planted. Birds, it seems, love these little fruits and deposit seeds everywhere they poop, particularly along fencerows and the edges of woodlands. The visual effect is very pronounced when the white flowers begin to blossom.

To most homeowners, this feels like a non-issue. They do not see the new seedlings as a problem. Weekly mowing of lawns and regular weed control in flower beds and other manicured properties keeps the plant from being noticeable in backyards. However, infrequently managed land (think fence rows, the edges of forested land, ditch banks, etc.), the Callery pear is beginning to appear in mass numbers. You can get a feel for the scope of the issue when you see the blossoms.

What can you do as the owner of ornamental pear trees?

First, I realize most people love their trees and are not going to chop down their ornamental pears just because the seeds are now viable. But in the event the tree dies or is seriously damaged in a storm, I encourage you to replace it with something other than a Callery pear.

For those who take this invasive seriously, but do not wish to cut the trees down, there are some fruit inhibitor products (e.g., ethephon, Florel Fruit Inhibitor) that can be sprayed to reduce fruit set. Note that timing and thorough coverage is critical. The spray must be applied when plants are in the early stage of full bloom, before fruit sets. Typically, ornamental pears are in bloom for 10–14 days. Unless you have access to specialized equipment, it will be difficult to provide thorough coverage on larger specimens.

I believe Indiana will eventually join a growing list of states, including Ohio and South Carolina, which have prohibited the planting of Callery pears. Some local nurseries have made the decision to no longer sell Callery pears. For now, it is up to the customer to make the decision to choose other species.

Bradford pear is not the only escapee from local landscapes that is causing issues. Nonnative versions of burning bush, Asian honeysuckle, some bittersweets and loosestrifes and several ornamental grasses are showing up in unmanaged area such as woodlands, fence rows and railroad right of ways.